Field of Invention
The present invention relates to condensers. More particularly, the present invention relates to a system and apparatus using ambient air and the cold from alternate sources including, but not limited to, waste cold from an industrial process such as, but not limited to, liquefied natural gas production to produce water.
Background
The hydraulic cycle describes the continuous movement of water on, above and below the surface of the Earth where water moves from one reservoir to another such as from the oceans and lakes to the atmosphere, through the process of evaporation, and from the atmosphere to oceans and lakes, through the process of condensation and precipitation.
Clouds are the most visible manifestation of atmospheric water, but even clear air contains vast amounts of water in particles that are too small to be visualized. It is estimated the atmosphere, at any one time, contains approximately 3095 mi.3 of water which calculates to approximately 0.04% of the Earth's freshwater, and apparently 0.001% of the Earth's total water.
Liquefied Natural Gas (LNG) is made from natural gas. Natural gas is composed primarily of methane (typically 85% to 90%) but also typically contains ethane, propane and heavier hydrocarbons (butane, pentane, hexane, etc.). Small quantities of nitrogen, oxygen, carbon dioxide and sulfur compounds are also found in most sources of natural gas, but the composition may vary with geological conditions. A large percentage of commercially available natural gas is produced in coastal areas globally such as, but not limited to the Arabian Gulf states and the United States Gulf Coast. In these geographic areas it is common for fresh water to be in short supply, but the surrounding ambient air is moisture laden.
Natural gas may be transported to consumers in a gaseous form via pipeline, however when distances between point of production and point of consumption is great, liquefaction of the natural gas (to reduce its volume by a factor of approximately 600) becomes economic. Liquefied Natural Gas (LNG) is formed when natural gas is cooled to temperatures of between −159° C. to −162° C. at atmospheric pressure. At these temperatures and pressure gaseous natural gas condenses to a cold liquid.
Natural gas is liquefied through a process that involves purification, chilling and liquefaction. The first step in the process is removal of H2O, CO2 and acid gases such as hydrogen sulfide which, if not removed would freeze into solids and cause blockages.
The second step is chilling the natural gas to moderately low temperatures of about −35° causing condensation of heavy hydrocarbons, (notably propane and butane) which might also freeze into solids and cause blockages.
The third step is liquefaction which occurs when high-pressure liquid refrigerant is depressurized through an expansion valve. The temperature reduction is used to extract heat from the natural gas through a heat exchanger causing the gaseous natural gas to condense into a liquid.
The liquefied Natural Gas (LNG) is piped, or otherwise transferred, from the heat exchangers to tanks where the LNG may be stored. Storage pressures in such tanks is low, typically less than approximately 5 psi. Insulation on and about the storage tanks is not efficient enough, by itself, to keep the LNG sufficiently cold to remain a liquid. LNG is therefore stored as a “boiling cryogen” which utilizes a phenomenon known as “auto refrigeration” where the LNG stays at a near constant temperature if kept at a constant pressure. This constant temperature is maintained so long as the LNG vapor “boil-off” is allowed to exit the storage tank. The vapor is either removed and used as fuel or is reliquified and returned to the storage tank.
The cold vapor off-gassed from the LNG is an energy source because it provides a temperature differential between the cold LNG and the surrounding atmosphere. This temperature differential provides a power source for the instant system and apparatus for atmospheric water generation.
The instant invention uses a unique thermal transfer media formed from synthetic carbon graphitic foam such as that described in U.S. Pat. No. 6,033,506 to Klett for Process for Making Carbon Foam and its related patent applications and issued patents as its means for capturing, transferring, and using the cold for water generation.
The thermal transfer media is light weight, weighing on average approximately 3-15 lbs. per cubic foot and is highly thermally conductive with a conductivity of up to approximately 1,800 W/m.K (watts per meter Kelvin) as compared to Copper (Cu) which has a thermal conductivity of approximately 400 W/m.K. Further, the thermal transfer media is highly electrically conductive nearly matching the electrical conductivity of copper.
The carbon graphitic foam thermal transfer media is produced by high-temperature treatment of amorphous carbon materials. The primary feedstock for making synthetic graphite is calcined petroleum coke and coal tar pitch, both of which are highly graphitizable forms of carbon. The manufacturing process generally consists of mixing, molding, and baking operations followed by heat-treatment to temperatures between approximately 2500 C and 3000 C. The heat drives the solid/solid, amorphous carbon-to-graphite phase transformation. The morphology of synthetic graphite varies from “flaky” in fine powders to irregular round grains in coarser products which is caused by high temperature vaporization of volatile impurities, which include most metal oxides, sulfur, nitrogen, hydrogen, and all organic components. The thermal transfer media may be formed into solid shapes of nearly any configuration.
The atmosphere contains moisture, and the moisture content is dependent upon the air temperature. In general, the warmer the air, the more moisture the air is capable of carrying. Likewise, the cooler the air, the less moisture the air is capable of carrying. Water condensers operate using “dew point” and temperature difference.
Condensers remove moisture from the air by “taking in” warm moisture laden air, and cooling the air to a temperature at which the air can no longer contain the moisture. Upon cooling, the moisture condenses to a liquid which may be collected. The cooler, dryer air is removed (vented outwardly) and more warm moisture laden air is “taken in” as the process continues.
One drawback to known condensers is the need for enormous energy input to reduce the temperature of the moisture laden air to cause “condensation.” The energy input is generally provided by an external electrical sources or generators which power compressors to drive a refrigeration apparatus. The power input required for the refrigeration process has historically made condensers expensive, complex and at times uneconomical.
The instant invention utilizes cold from alternate cold sources including waste cold from industrial processes, including but not limited to liquefied natural gas (LNG) production as the energy input for condensing moisture from air.
For purposes of this patent disclosure the cold source is cold from the production of Liquified Natural Gas (LNG) however other sources of cold are expressly contemplated as well and may similarly be used as a cold source for the instant invention. Other contemplated cold sources include, but are not limited to, cryocoolers and acoustic wave form engines such as those manufactured and sold by Qdrive™/Chart Industries of Troy N.Y., USA, Stirling refrigerators, GM refrigerators, Pulse-tube refrigerators, and Joule-Thomson coolers. The cold may be intentionally generated or waste cold.
The instant thermal transfer media is used to wrap, enclose or otherwise communicate with a cold source including transfer means and storage apparatus containing LNG. It is further contemplated the thermal transfer media may be exposed, directly or indirectly, to the LNG and/or the “boil-off” vapors of LNG. The cold of the apparatus containing the LNG, or the “boil-off” vapors is thermally transferred to a condenser apparatus, using the thermal transfer media's properties of thermal conductivity.
A plurality of through pores defined in the carbon graphitic foam thermal transfer media which are created during the formation of transfer media dramatically increase the amount of surface area available which even further enhances the thermal conductivity of the material. The thermal conductivity works in two “directions”, first by transferring the cold from the cold source into a condenser apparatus to cool the warm moist air flowing thereover and thereabout to a temperature below the air's dew point, and also to cause the thermal transfer media to absorb heat/warmth from the warm moist air flowing thereover and thereabout to cause any ice crystals that may form on the thermal transfer media, or in the pores to melt into liquid water for collection. The high thermal conductivity of the thermal transfer media enhances both aspects of producing water from ambient air, namely the cooling of air below its dewpoint, and the melting of ice crystals formed on the thermal transfer media into liquid water.
The size and number of the through pores may be optimized during the manufacturing of the thermal transfer media to further enhance thermal conductivity and to optimize use in particular situations, configurations, and environments such as, but not limited to, increasing the number and size of the pores, by reducing the size of the pores while maintaining a high number of pores, by reducing the number of pores while increasing the size by reducing the number of pores and the size of the pores or variations thereof. The densification of the thermal and carbon media may be adjusted, altered and optimized to best suit particular conditions/installations.
Within a condenser container which defines an Interior volume, the thermal transfer media is formed into a body which may have a configuration of a hollow cylinder with cooling vanes thereon or the like. In another embodiment the body may carry a plurality of thermally conductive plates in spaced array. The plurality of plates may be formed from the thermal transfer media, or other thermally conductive materials such as, but not limited to copper, and are interconnected to the body so that thermal energy is passed by conduction from the body to the plates/vanes causing the plates/vanes to cool. The plates/vanes have a greater surface area than the body and therefore have greater ability to cool a larger volume of moisture-laden air passing thereover and thereabout. One preferred configuration of the condenser is that of an “inverted cone” formed of plural spaced apart parallel plates with larger diameter plates at the highest vertical level and each lower plate having a smaller diameter.
An air moving system, employing known HEPA type filters draws a continuous supply of warm moisture laden air from the exterior the container into an interior volume defined by the container. A plurality of thermal transfer bodies may be carried in spaced array within the volume of the container. As warm moisture laden air passes over and about the thermally conductive plates, moisture within the air condenses upon the cold plates and falls, under the power of gravity to a collection basin maintained thereunder. Moisture collected within the collection basin is then “piped off” to a storage facility for later use. The HEPA filters, having previously removed all airborne contaminants cause the condensed water to be of potable quality.
The instant invention has minimal moving parts and may use waste cold that is otherwise lost and wasted to the environment as well as intentionally generated cold.
The instant invention provides a thermal transfer media to efficiently capture cold and transfer the cold to condensing apparatus for condensation of moisture from ambient air.
The instant invention provides a means for using waste cold as an energy source.
The instant invention provides means for producing water from ambient air using low energy input and environmentally sensitive apparatus.
Some or all of the problems, difficulties and drawbacks identified above and other problems, difficulties, and drawbacks may be helped or solved by the inventions shown and described herein. The instant invention may also be used to address other problems, difficulties, and drawbacks not set out above or which are only understood or appreciated at a later time. The future may also bring to light currently unknown or unrecognized benefits which may be appreciated, or more fully appreciated, in the future associated with the novel inventions shown and described herein.